697 research outputs found
Data of cryocooler temperature dynamical response to time-varying power inputs at 4 K
No full textData presented here deal with the measurement of a two-stage Gifford-McMahon cryocooler dynamical thermal response to programmed square wave and sine wave power inputs around 4 K. Square response data report the raw temperature data points measured by the sensor. Properly filtered data are also presented and results of exponential decays fitting analyses are shown as well. Sine response data were acquired with two different experimental setups and at several frequencies; data report the frequencies of the input stimulus, the measured temperature variation and the phase between input and output signals for both setups. More details about the experimental background can be found in the related research article, “Experimental analysis of the thermal behavior of a GM cryocooler based on linear system theory” (Sosso and Durandetto, in press)
Determination of the temperature vs power dynamic behavior of a cryocooler via two independent methods in time and frequency domain
No full textThis report deals with the analysis of a cryocooler as a linear dynamical system around a set point, over a range of temperatures where the thermal properties can be considered constant.The accurate knowledge of the cryocooler temperature dependence with a time dependent power stimulus allows to analyze the thermodynamical properties of the system and understand the power flow related, for example, to the cryocooler temperature fluctuations. This is useful for the design of efficient thermal dampers that are necessary for the thermal stabilization of the device under test Sosso et al. [1], Trinchera et al. [2]. Two different and independent methods for deriving the cooler dynamic (i.e. non-stationary) behavior are described using the two main approaches to mathematically represent a dynamical system: step response and transfer function. • Using both approaches we were able to cross check results and provide an estimate of the accuracy of each method. • The instrumentation required is typically available in physics and engineering laboratories. • These results provide insights on cryocooler thermodynamics and design tools for cryocooler engineering. Method name: Temperature to power dynamic response of a cryocooler with both time and frequency domain analyses, Keywords: Cryocooler analysis, Transfer function, Step respons
Experimental analysis of the thermal behavior of a GM cryocooler based on linear system theory
No full textClosed cycle refrigerators for cryogenic temperatures (cryocoolers) provide a convenient solution in a wide range of applications, from low temperature physics to cryopumping, superconducting magnets or low noise infrared sensing. Understanding in detail the physical mechanisms underlying cryocooler operation is then of practical and fundamental interest. This paper deals with the analysis as a linear dynamical system of a GM cryocooler operation, considered over a limited range of temperature around a setpoint. The method is interesting as a way to model the thermal behavior of the refrigerator that can be effective in systematic analysis of cryocoolers thermal behaviour and design of temperature controllers
Phase lock of non-hysteretic Josephson junctions with pulse bias: analytical properties
No full textThe behaviour of a non-hysteretic shunted Josephson junction can be
described by a differential equation admitting analytical solution in
the constant-current bias case. Studying the pulse bias as a sequence of
constant-bias states we were able to derive expressions for the
phase-lock condition and to study some relevant features of Shapiro
step
Preliminary studies for the realisation of an electrometer transducer for mass measurements based on fundamental constants
No full textExploiting First and Second Shapiro Steps Towards the Reduction of Bias Lines in Programmable Josephson Arrays
No full text
Towards a He-Free Source of Arbitrary Quantum Voltage Signals
No full textThe Josephson effect is worldwide exploited as the basis for constant reference voltages in National Metrological Institutes (NMIs) and in industry calibration laboratories. Lately, voltage metrology research has been mainly directed towards the application of Josephson effect for the synthesis of very accurate ac and arbitrary voltage signals: pulse-driven Josephson arrays represent the most promising way for linking ac voltage calibrations to a quantum phenomenon. Furthermore, an easy and secure cooling system based on cryocoolers is desirable in order to allow the spread of Josephson standards outside NMIs. A Gifford-McMahon cryocooler is currently in use at INRiM for the operation of ac-Josephson Voltage Standards (JVSs). We employed pulse-driven JVSs for synthesizing sine waves with frequency in the kHz range and amplitudes in the mV range, with distortion around 80 dBc. In this report we present a detailed description of this technique and of the refrigeration system employed
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